Gas springs may be utilized to yieldably resist movement of a body such as a clamping ring for a metal blank of a die in a press for forming sheet metal parts. The springs are generally constructed with an actuating rod connected to a piston, slidably received in a cylinder having a chamber charged to a predetermined pressure with an inert gas such as nitrogen. This provides a spring effect or cushion permitting the rod to yieldably move toward its retracted position when a force applied externally to the rod exceeds the opposing force produced by the gas in the chamber acting on the piston. The gas springs can be operated with either an external source of gas or can be precharged and operated as a self-contained unit.
In use, as the piston approaches its retracted position, thereby decreasing the volume of the gas chamber, the pressure within the chamber may increase to between 3,000 and 5,000 psi or more. To maintain the axial movement of the piston rod and also to ensure a sufficient seal of the gas spring to prevent pressure losses in the gas spring, current gas springs have bearing, sealing, and retaining members which are relatively large and thus reduce the internal volume of the gas chamber within the gas spring. The smaller gas chamber leads to increased pressure and also increased temperatures within the gas spring which can be detrimental to the operation of the gas spring. Thus, the gas spring must be made larger in size to provide a sufficient gas chamber volume.